Method of performing power control in mobile communication system

Abstract

Provided with a method of performing power control in a CDMA mobile communication system, characterized by including the steps of: repeatedly updating information concerning the change of a channel state between a mobile station and a base station at regular intervals; varying a channel gain up / down time and / or a channel gain up / down delta adaptively based on the updated information; and adjusting the channel gain between the mobile station and the base station.

Description

1. Field of the InventionThe present invention generally relates to a method of performing power control in a mobile communication system using the code division multiple access (CDMA) scheme. More particularly, it relates to a method of performing power control which is designed to adaptively control transmission power supplied from a base station to a mobile station (terminal station).2. Description of the Related ArtIt is of much importance to maximize the capacity for concurrent communications with multiple mobile stations in a frequency band supplied to a CDMA mobile communication system. A method of maximizing the capacity of a given system involves performing power control of the mobile communication system. Such methods are classified into two parts: a forward link power control for transmission power received by the terminal station from the base station, and a reverse link power control for transmission power received by the base station from the terminal station.During th...

AI Technical Summary

Benefits of technology

Furthermore, the downward adjustment of channel gain is performed in such a way that the downward cycle is variable in multi-steps within a predetermined range to provide the optimal downward cycle based on the channel state, making it possible to track the change of forward channel power required by the mobile station, with the consequence of a reduction of unnecessary power consumption and enhancement of FER performance with respect to power consumption.

Problems solved by technology

During the forward link power control, the mobile station located at the edge of a cell has to consume much power enough to maintain service quality to the same level as the mobile station located at a position near the base station, which is called "coner problem".

Especially, the power assigned to the mobile station affects the other mobile stations as a noise in the CDMA system.

The surplus power affects the signals received from the other mobile stations as a noise especially in the CDMA mobile communication system.

However, it is problematic in an environment where the channel status has large variations such as in the case the mobile station passes through a shadowing area, as illustrated in FIG. 1.

Contrarily, in a case where the gain down time is set very long enough to be suitable for the channel status shown in FIG. 3, the downward tracking time 111 in the channel status of FIG. 1 gets prolonged to cause unnecessary power consumption, which affects as a noise the mobile stations in the cell which is adjacent to the other mobile stations therein.

This causes the channel capacity of the entire communication system to be reduced.

Additionally, the conventional method involves another problem that the adjustment conditions cannot be applied precisely during an upward adjustment of the channel gain.

If the FER exceeds the threshold, the channel gain is increased by the current big up delta. If the FER is below the threshold, the channel gain is decreased by the current small up delta. However, it often happens that the channel gain increases by a big up delta even when it can be increased by a small up delta, in which case unnecessary power consumption is caused to adversely affect another mobile stations in the cell and the mobile stations in another cell.

This may appear very often especially when frame errors occur continuouslly.

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